Dogs and cats with long-standing skin or gastrointestinal troubles may be suffering food allergy. Once you’ve dispelled the myths surrounding food allergy, you’re ready to test. If you’re really serious about identifying a dietary allergen, forget expensive and unreliable blood tests, and go straight to a food elimination trial. If the response to this temporary diet is good, you’re already halfway to fingering the offending ingredient, excluding it, and solving your allergy problem. Unlike humans, who quickly grow bored and break dietary rules, pets often happily dine year-in, year-out, on the same old low-allergy diet.
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What is your pet allergic to?
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Diagnosing Food allergy: Blood test versus elimination diet
The use of blood tests for diagnosing food allergy is controversial. Commercial laboratories offer vets a blood testing service with an accuracy of up to 60%, at best. Many vet dermatologists view them as ‘absolutely useless’, resulting in false negatives and false positives, and elimination diet remains the gold standard for food allergy diagnosis.
If you’re lazy, impatient for an answer, and unphased by cost, do the blood test, but if excluding the identified allergen doesn’t seem to work, you’ll need to resort to an elimination trial anyway. I don’t recommend wasting your money on blood tests; spend it on an venison instead.
Principles of an elimination diet
Ingredients and recipes
Have as few ingredients as possible: preferably one source of protein, and one source of carbohydrate. The more ingredients, especially if commercial foods are included, the greater the likelihood an allergen may be inadvertently included in the elimination diet, ending in a false negative result.
Dogs should be fed a protein and carbohydrate that has rarely, if ever, been offered previously. Unusual protein sources are ideal, such as kangaroo, rabbit, duck, turkey, crocodile, or other game meats. Fish is a good choice as it’s also loaded with anti-allergy Omega-3′s. The offal of the protein source can be fed, but not that of other species. Protein can be served cooked or raw. Unusual carbohydrates are potatoes, rice or pulses.
An approximate recipe is 2 parts carbohydrate to 1 part protein. Protein content shouldn’t fall below 25%. While it’s tempting to incorporate other veggies, they’re not necessary in a short term trial.
Cats can receive a 100% protein diet, ideally containing a singular animal protein never previously fed. Kangaroo, rabbit, and turkey are good choices. Offal of the chosen species is ok. Carbohydrate, veggies and other ingredients are not necessary during the trial. If your cat is unwilling to eat the one species for the 6 to 8 week trial period, you may need to select 2 proteins, and alternate.
In both cat and dog, religiously exclude ingredients commonly used in commercial pet food such as beef, chicken, lamb (for dogs), soy, dairy, fish (for cats), wheat, oats, and corn. Dairy exclusion should encompass lactose-free milk products, manufactured for pets. Exclude all other potential food allergen sources including treats, rawhide and ear chews, flavoured medications, and bones (including those hidden in the garden).
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Avoid commercial foods
Ingredient lists can’t always be relied upon. Supermarket brands can contain a Noah’s Ark of unlisted protein and other ingredients. If life’s already busy enough, preparing meals for the family, and 2 months of homecooking for the pet isn’t feasible, there are a handful of commercial foods recommended by vets for an elimination trial. These cost 20-30% more than regular pet foods, and can be used alone or supplementary to a novel, fresh meat diet:
- Hills Prescription Diet Z/d or D/d – rice/egg
- Eukanuba Response Formula FP – fish/potato
- Royal Canin Therapeutic, feline: pea/duck, pea/venison, pea/rabbit, pea/lamb, or Hypoallergenic HP
- Royal Canin Therapeutic, canine: potato/duck, potato/venison, potato/rabbit, potato/whitefish, or Hypoallergenic HP
If however, your pets skin or tummy trouble fails to improve on these commercial diets, it is still possible a home-cooked, novel protein diet may be effective.
When to do an elimination diet
Most food allergies are perennial and the flow of seasons offers no relief. However, when a pet suffers multiple allergies,and some seasonality is observed, conduct the elimination trial a time of year when the skin is usually bad, so a therapeutic benefit is easier to detect. Ask your regular vet: your pet’s medical records will reveal the yearly pattern.
Duration of an elimination diet
If no improvement is observed during the first 6 to 8 weeks, then you can give up and accept the depressing reality: the allergen originates outside the foodbowl.
If there’s a partial response, with some improvement, but no cure, you can increase your certainty by pushing out the trial to 10-12 weeks, and see how good an outcome is achievable.
If a good response is observed, start celebrating, but don’t overlook the opportunity to get more information with the challenge, described below.
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Challenging after an elimination trial
Once you’ve established a diet which seems to have improved your pet’s health, it’s time to challenge with foods and look for symptoms to return. This is important, to firm-up our confidence the diet actually worked, and identify the exact allergen(s).
Understandably, once a food allergen is excluded and long-standing symptoms begin to clear, some pet owners are reluctant to enter a challenge phase. Relieved from chronic skin disease, they don’t ever wanna go back, and are happy to stick with the fish and potato, or other recipe, used in the trial. The trouble wih this approach is:
- Failure to identify the allergen, so all future dietary decisions are made in the dark. Fingering individual allergen(s) offers greater flexibility when selecting commercial foods and formulating homecooked recipes.
- Home cooked diets are often unbalanced. This is especially important in young, rapidly growing dogs, and cats living on 100% fresh meat diets. Having at least a small amount for commercial food in the daily ration is like giving a multivitamin. For more, see The Arguement for Dietary Diversity.
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Two techniques for challenging
1) Scientifically test for the allergen, using staged re-introduction of ingredients, one-by-one. It can take between 2 days and 2 weeks for symptoms for reappear after introducing a food allergen, so don’t add a new ingredient more frequently than one every 2 weeks. Test all the major allergens starting with beef, chicken and lamb, fish for cats, and then check dairy, eggs, and pasta for wheat.
Cases of multiple allergy are rare, but if you discover one, continue to test the others. If no symptoms return, you have to question if the response to elimination diet was real, or if the skin problem spontaneously resolved, coincidentally. Once the allergen is fingered, you can start scrutinising labels and testing their claims wih your beef-detecting dog.
2) More crudely, experiment by offering commerical diets. As these represent a pot-purri of potential allergens, listed on packaging and unlisted contaminants, this process is very hit-and-miss. This option is often favoured by pragmatic pet owners, impatient to move onto kibble or tins ASAP, and relax after 2 months of labourious dietary rules.
Best to start with some of the higher quality, novel protein diets listed above, and then gradually move to cheaper, riskier petfoods, if desired. When symptoms return, guess which is the offending ingredient.
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If you’re lucky, after 3 months of scouring butchers for exotic meats, boiling rice and potatoes, and getting dirty looks from a fussy cat, you may be liberated from the treadmill of derma-pharmaceuticals. If you see no such reward, it’s no waste of time, as you can slap-down the vet when ever he mentions the possibility of food allergy.
Tags: allergies, allergy, animal research, beef, blood tests, canine, carbohydrate, cat, challenge, chicken, commercial pet foods, corn, dairy, dermatitis, diet, DIY, dog, ear, egg, elimination, elimination diet, Eukanuba, feline, fish, fish-based diets, food, food allergy, fresh food, Hills, home cooked, itch, kangaroo, novel, nutrition, oats, Omega-3's, paw, pet food, potato, protein, rabbit, recipe, rice, Royal Canin, soy, trial, vension, vet, veterinary, wheat
wow, what an impressive post Matt – but can those cows yodel – or get down and boogy?
I’ve linked to this page on today’s belly post
Email conversation with Jennifer, cat owner, Nth Carolina.
have you ever seen food allergy (EGC) symptoms recur only after 30 days of the food challenge? I see “3-14 days” all over the internet. My cat’s EGC disappeared after: winter season, allergy shots for dust mites/mold, and rabbit/pea. He was fine for months, then I rechallenged with original food May 2 and symptoms (rodent ulcer) appeared June2. (As on his face we noticed the day it started to appear.)
Is symptoms after 30 days back the original “challenge” diet simply out of the question for a food allergy? He now refuses to eat the rabbit/pea diet again…we hate to go down the whole food route again unless really necessary..treating the EGC topical steroids from our vet.
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hi jennifer,
the 2w deadline is a little simplistic and there would be a ‘normal distribution’ with the majority showing recurrent allergy within 14 days, but a smaller number earlier and later. A very small number may take up to month to recur.
Even though traditional wisdom states there should be a response to an elimination diet within 6weeks, a recent article out of Ireland reported there were small numbers of cats that responsed to z/d only after 6 months on an elimination trial!.
If your uncertain, I would look for repeatability: if you see return of the rodent ulcer after a month, or even longer, on a second rechallenge, or a third, you can definately be more sure its a dietary effect.
cheerio
Dr Matt Allworth, BVSc
http://www.communityvet.net
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Hi-
Just to let you know, we did change the cat (granuloma had recurred on original diet but only after a full 4 wks) back to the rabbit and pea “novel protein” that he had been eating in the winter/spring, and within a week or so he started to improve. He is granuloma-free now- it took about 4 wks to completely go away and he’s been fine now, about 7 weeks on this diet. Last year he had granuloma this same time of year so I don’t think it’s a seasonal effect- I think it returning to the novel protein diet.
A note: this cat has been on allergy shots for inhalant allergies since last November (also on the rabbit/pea diet, until I tried him on the Friskies again in May). He did well on both the shots and the rabbit pea diet all last winter/spring. I think maybe this might be part of the reason the food allergy took a full month to show symptoms- maybe the shots are protective to some degree and he had to really build up a lot of antibodies to the food before he showed symptoms? The shots are reported to have a non-specific immune-mediated inflammation -dampening effect.
At any rate the cat is doing great on the allergy shots and rabbit/pea diet. Wish I had changed back to the rabbit/pea diet weeks earlier, I didn’t realize it could take a month to show symptoms!
Thanks for your helpful comments!
Jen
North Carolina
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hi jennifer, good to hear youve made progress. The allergy is probably multifactorial with seasonal environmental and dietary contributors. If its too expensive or too boring for the cat to remain on the hypoallergenic diet all year round, you maybe be able to give the diet just during the seasons when the skin problems flare.
Dr Matt Allworth, BVSc
http://www.communityvet.net
Hi,
I am trying an elimination diet of Hills d/d (Venison & pea) but my cat doesn’t like it. He eats it when he gets really hungry but then he is still vomiting. This is after a week. I have read that you have to keep these diets going for 8-12 weeks but if he is still vomiting, and losing wieght how can we possibly keep it going that long? We have tried giving him zantac but we can’t get him to take it. We forced it down him for a couple of days and he got better but as soon as we stopped he started vomiting again. It was really traumatic forcing it down him. Have you got any suggestions?
Thanks
hi sally, complex one. is he young or old? are there any signs (thirst, diarrhoea, malena, wt loss, lethargy) it could be a more serious disease causing the vomiting (renal, hyperthyroid, diabetes, cancer, etc). palatability can be a big problem with cats, and some will go hungry for days in protest.
zantac may offer symptomatic relief, but it alone is never going to cure and identifying the cause of the vomiting (response to diet, or blood tests/scoping/imaging) is the only sustainable solution. especially demoralising if your having to force it down.
he may be reactive to commercial/dry foods, so trying on a whole meat diet may help with the vomiting. If you find he responds and vomiting stops and gains wt, you may then be able to experiement with commercial foods, to find one he can tolerate. If vomiting returns go back to the fresh, whole meat diet.
If there are any of the signs of more serious disease, describes above, please involve your vet. If hes thirsty, take in a urine sample…..
http://communityvet.net/2009/12/liquid-gold-saving-time-and-money-with-urine/
Hi, THanks for your reply. he is 8 years old, same equivalent as me, so not very old! We have had the vet involved – he prescribed zantac. He isn’t any more thirsty than normal. THe vet admitted that it must be more than just a food problem. he had blood tests for liver & kidney problems which wre OK. Panceatitis test showed white cell count a bit high but they said this was probably because he was n such poor condition – dehydrated etc when the test was done. Today he had an X ray. No lumps or growths or blockages but something is odd with his small intestine, it had some sections that looked like they may not be working properly – maybe thickened or an odd shape, I don’t really know. So the vet thinks this is why he is being sick all the time but doesn’t know what is wrong with the intestine. The large intestine is OK. He took more blood for more tests and now we have anti-biotocs and zitac tablets (quarters) to try to get down him. If the anti-biotics and zitac don’t fix him after a week or so he might have a biopsy of the intestine. Will keep you informed…
i’d be putting my money on Inflammatory bowel disease (IBD), which can be a severe form of food allergy that may need cortisone to treat. Other infiltrative diseases such as lymphoma are also possible. If the eosinophil count is up it may still be an allergic mechanism and persisting with a hypoallergenic diet may yet prove to be helpful. Unfortunately bowel biopsy may be the only definatively diagnosic endpoint. I’ll be interested to hear of the outcome.
Hi,
In the end we had the vet open him up and look at his intestines and stuff. They took 20 biopsies of the intestine. After a week, the results came back – severe duodenal ulceration. They didn’t see any ulcers on the X-ray but they are pretty sure this is the probem because they found them in the biopsies. He had Metacam for 5 days after the op, and a long term (2 weeks) anti-biotic injection. So now we have Jeeves on Hills i/d meat which he’ll lick up the gravy with a quarter of a Pepcid tablet crushed in, and he really likes Hills i/d biscuits. He continued to be sick for another week on Hills d/d biscuits (he hated the d/d meat). The d/d biscuits just didn’t seem to be digested – a huge amount came up several hours after he had eaten. So we swapped to i/d biscuits and continues with the Pepcid and now he has not been sick for a whole week. He is slowly getting back to his old self. We were so lucky it wasn’t lymphoma, but we don’t know what caused the ulcers and they could come back I suppose. So we think things are going to be OK. Thanks for your help.
Hi Matt.
I have a 9 year old cocker spaniel that is amazing but has constant skin infections, black spots on his body, lipfold infection under the chin etc. so we have decided to try the elimination diet. We have chosen turkey and sweet potatoe…
my question is how much to feed him??? He is 33-34 lbs. and loves to eat…no matter how much we give him he always wants more. I read the 2:1 ratio for carbs/protein but how much protein should he be getting and how many times a day should we be feeding him?
should the food be raw or cooked? can I give him raw turkey bones? frozen yam so that he uses his teeth? Is 3 weeks too much to keep him on this program without vitamins?? Sorry for all the questions but I want to help my dog, not make him sick.
Thanks.
hi ava, chelitis, or lip fold infection can be a stubborn problem in cockers, and not commonly dietary responsive, but an elimination diet wont do any harm and may help his skin more generally.
When formulating a ration, start with the protein, and a good rule of thumb is 2g of meat protein per kilo of body weight per day. A 15kg cocker will need 30g of meat per day. You can then work backwards to give 2 times this volume of sweet potato. If you’re concerned this portion seems too small, just keep an eye on his body weight, if it starts to drift down at week 2 you can slightly increase the ration.
Dont worry about nutritional deficiencies during a trial period of 3 weeks, or even up to 6 weeks. Our bodies are very well adapted to coping with seasonal variation in foods.
Cooked or raw doesnt matter, and turkey bones are ok. You could give yams frozen, but i can reassure you his teeth will not markedly deteriorate during a 3-6w period if dental abrasion is absent. read more on this at Bones of contention….